Previously, most optical waveguides were typically fabricated of insulating materials such as Si3N4 or SiO2. With the development of silicon-on-insulator (SOI) technology, silicon waveguides on SiO2 have become practical for transporting micrometer-wavelength radiation. Since these waveguides may be doped and made conductive without inducing excessive optical loss in transmitted signals, a variety of electrooptic devices have been made utilizing SOI technology that could not be realized with insulating waveguides. To date, these devices have typically utilized external means for intensity and polarization control and modulation. Furthermore, these waveguides typically exhibit optical loss from light being scattered out of the waveguide and being absorbed by chemicals at the silicon waveguide surface.
Accordingly, there is a need for methods and apparatus utilizing these technologies that do not require external means for polarization control and modulation and a low power means of modulating and reducing optical loss.